Randymon....flying standby question

My hubby works for an airline and we are flying free. I want to do the online check in, but since we fly stand by, we are never 100% sure what flight we will be on. We know the airline, of course. On the way down, we know the airport we are leaving from, but on the way home, we may have to fly into a different US city.

So, for online check in, should I just put the earliest possible flight we will be arriving on and leaving on?

If we do that, should I call or email someone if we don't make it on that first flight and we will be arriving later? I don't want anyone wondering where we are if we don't arrive at MBJ on the flight we wrote down.